Morphology of neurons in the anterior hypothalamic area and supraoptic hypothalamic nucleus of the adult human brain.

Morphological features of neuronal cell types in the anterior hypothalamic area (AHA) and supraoptic hypothalamic nucleus (SON) of the adult human brain were analysed in Golgi impregnated preparations. Four neuronal cell types were described for the first time in these human nuclei. Type I neurons were found in both the AHA and SON, while the other three cell types (types II-IV) were found only in the SON. Type I neurons had elongated, triangular or multipolar somata, which emitted 2-5 sparsely branching primary dendrites with a moderate number of fine spines. Also many of type I neurons in the AHA had thin dendritic side-branches. Type II neurons had round or fusiform somata, and two occasionally branching primary dendrites. Type III neurons were multipolar neurons with 3-5 densely spined and sparsely branching dendrites. Their axons had collaterals. Type IV neurons had very small ovoid somata with one smooth and unbranched primary dendrite. The neurons in the human AHA and SON were similar to those observed in the same areas in other mammalian species, except for the very small neurons in the SON and the thin dendritic side-branches of type I neurons in the AHA, that had not been previously described.